1. Field of the invention
This invention relates to extracting moieties from a process stream, and more specifically, this invention relates to a system of solvent extraction using a combination of an electrochemical cell and a microfluidic chip to isolate a particular element or compound from a mixture of elements or compounds.
2. Background of the Invention
Waste streams and process streams need to be monitored regularly to determine system efficiencies and to assure environmental safety. Some process streams are more difficult than others to monitor. Nuclear process streams are the difficult ones, particularly if these streams are to be monitored in real time. For example, on-line and real time monitoring of process streams containing complex mixtures of lanthanides and actinides is difficult given that these mixtures often produce interfering signals prior to analysis. Rare earth element processing plants and nuclear material treatment facilities pose significant challenges.
Liquid-liquid extraction, or solvent extraction, may be used to separate moieties in process scale applications. Solvent extraction involves the use of two different immiscible liquids where extraction occurs as the desired substance moves from one liquid phase to another liquid phase. This process is expensive given that large volumes of extraction fluids are used and that the samples must be sent to a laboratory for processing. Also, process scale fluid volumes prevent the use of microscale equipment inasmuch as the processing of large fluid volumes are associated with relatively large Reynolds numbers (i.e., chaotic fluid flows and other instabilities) which are not tolerated by the smaller reaction chambers defined by microscale equipment. As such, real time determination of target moiety concentrations are not possible with state of the art macro-scale processing.
A need in the art exists for a low-cost system for determining moiety concentrations in process streams that is capable of being performed at the microliter scale. The system should enable real-time process control of refining plants as well as the inexpensive production of small volumes (between 5 microliters (μl) and 20 μl) of slip stream aliquots) of high purity substances from slip stream aliquots derived from nuclear and rare earth process streams.